A variety of body support structures have been developed ranging from rigid fixed structures, for example wood or metal benches, to entirely fluid structures, such as hammocks. One type of body support structure is a membrane suspended over or between a frame, such as the backrest and seat embodied in the Aeron® chair developed by, and available from, Herman Miller, Inc., Zeeland Mich., the Assignee of the present application. The suspended membrane provides a high level of adaptivity and aeration, which are primary contributors to the comfort of the user. Typically, the deflection pattern for this type of suspension structure offers more flex in the middle of the support surface than at the edges, where the membrane is supported by the frame. It may be difficult to provide the body support surface with any contour, for example along any particular cross-section between frame members. In addition, the frame presents a relative rigid structure along the periphery of the support region.
Another type of body support structure is a molded polymer structure, such as the backrest embodied in the Mirra® chair developed by, and available from Herman Miller, Inc. Often, such structures are preshaped and frameless, with a three dimensional contour molded into the structure that conforms to the body of the user, thereby aiding in the distribution of the load applied by the user. The deflection capabilities of the structure may be predetermined by way of controlling a number of variables, including the material of the structure, the thickness thereof, the presence of holes, etc. While such structures may be covered with a fabric, the fabric typically is secured only around a peripheral portion of the molded back so as to not adversely affect the flexibility thereof. Such molded backs typically are less adaptive to applied loads than the suspended membrane structure described previously. At the same time, the molded component does not require a support frame, and may therefore be more adaptive at the periphery thereof.